A developer cartridge used in a laser printer and other image forming apparatus are generally divided into two types: an all-in-one cartridge and a split cartridge. The all-in-one cartridge is formed by a combination of a developing unit and a processing unit permanently connected to each other, and is used as one assembled inside the laser printer. The split cartridge refers to a developer cartridge in which the above developing unit and processing unit can relatively be removed by a user, and the developing unit can be individually replaced. The developing unit mainly comprises a developing unit frame, a developer chamber, an agitator, a toner supply roller, a developing roller and a toner deposit blade. The agitator, the toner supply roller and the developing roller can be rotatably assembled on the developing unit frame. The processing unit mainly comprises a processing unit frame, a waste toner chamber, a photosensitive drum, a charge roller and a cleaning blade. The photosensitive drum and the charge roller can be rotatably assembled on the processing unit frame. In the developing unit, the developer chamber provides a developer storage space and an appropriate developer transmission channel; the agitator can make a stand-by developer exported to the developing roller to be uniformly distributed through its own rotation; and the developing roller adjacent to the photosensitive drum makes the developer to be adsorbed to the electrostatic latent image region on the photosensitive drum through the role of opposite polarity charge. The charge roller of the processing unit provides charging to the photosensitive drum causing the photosensitive area of the photosensitive drum to carry the charge with the opposite polarity to the developer's adsorbed charge. The cleaning blade can frictionally contact with the photosensitive area's surface of the photosensitive drum through visual image transfer and scrape the remained developer on the photosensitive area's surface of the photosensitive drum into the waste toner chamber.
Chinese Utility Model Patent Number CN2755647Y discloses a developer cartridge that can be removably mounted on a main assembly of an electrophotographic image forming apparatus. The specification of the patent describes the overall structure of the developer cartridge in detail. The main assembly comprises an output contact movable between an electrical connection position and a retracted position, a mobile member used for moving the output contact, and a flexible function member used for flexibly pushing the mobile member toward the retracted position to push the output contact. The developer cartridge comprises an electrophotographic photosensitive drum, a processing device acted on the photosensitive drum and a movable operational member moved relative to the developer cartridge's frame, in which the movable operational member can connect with a permanent connecting member and move relative to the cartridge frame when the developer cartridge is inserted into the apparatus main assembly. And after said connection, the movable operational member can connect with the movable connecting section of the mobile member to make the output contact to move from the retracted position to the electrical connection position by overcoming the elastic force. An input electrical contact is used to receive the connection via the output contact moved to the electrical connection position to start the processing device's voltage. The developer cartridge uses too many electrical connection accessories with complex structures. Thus, the use of a large number of molds is required, its production procedure is so long, and the product assembly process is relatively long and complex.
As shown in FIG. 1 and FIG. 2, an existing developer cartridge 1′ is formed by a combination of a developing unit 2′ and a processing unit 3′ connected to each other. The frame of the processing unit 3′ provides a conductive film 4′ and a conductive film bearing 5′ at one longitudinal end of a charge roller inside the processing unit 3′ (not shown). The conductive film bearing 5′ extends downward to form a bearing plate 6′. The bearing plate 6′ has a left side and a right side parallel to each other, and a bottom perpendicular to the above two sides. The width of the bottom is the thickness of the bearing plate 6′. The conductive film 4′ has an input 41′, an output 42′ and a transmission section 43′ connecting the input 41′ and the output 42′. The input 41′ is electrically connected to the output 42′ through the transmission section 43′ and connected to the charge roller in order to provide pre-charged bias for the charge roller. The input 41′ has a middle contact plate 44′ shaped like a bent strip. The middle contact plate 44′ comes in close contact with the bottom of the bearing plate 6′.
In the above developer cartridge, the conductive film bearing 5′ and the bearing plate 6′ formed from its extension are existed in a naked and permanent state. An electrical contact of the image forming apparatus main assembly is also existed in a permanent state. Referring to FIGS. 3, 4 and 5, when the developer cartridge is assembled inside the image forming apparatus main assembly and assembled in place, the middle contact plate 44′ of the conductive film 4′ can contact with the electrical contact 7′ of the image forming apparatus main assembly in its permanent position state to achieve the electrical connection without other extra accessories thereby reducing the complexity of device structure and helping to improve the stability of electrical contact. However, since the conductive film 4′ wraps the bearing plate 6′ in a single side and contacts the electrical contact 7′ only through the middle contact plate 44′ with smaller width, and the electrical contact 7′ suitable for the developer cartridge in the image forming apparatus main assembly is usually a thin and long metal wire with much smaller width, the scenario in which the electrical contact 7′ offsets toward both sides of the middle contact plate 44′ as shown in FIG. 4 and FIG. 5 can occur when the developer cartridge is assembled inside the image forming apparatus main assembly and assembled in place. Thus, the phenomenon of bad contact with the middle contact plate 44′ occurs. As a result, the image forming apparatus main assembly cannot induce the developer cartridge.